Paramutation: The chromatin connection
Paramutation: The chromatin connection
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DOI：
10.1105/tpc.160630
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发表时间：
2004-06-01
期刊：
影响因子：
11.6
通讯作者：
Cone, KC
中科院分区：
文献类型：
--
作者：
Della Vedova, CB;Cone, KC
自从RA Brink描述了r基因座的一种可遗传的改变，这种改变违背了孟德尔遗传的原则（Brink，1956）以来，对玉米中的平行突变进行了广泛的研究。最近关于玉米中的副突变的出版物现在提供了令人信服的证据，即染色质水平调节是参与副突变的等位基因之间的表型差异的基础（Stam等人，2002年a）。另外两篇文章--一篇详细介绍了与哺乳动物印记相关的副突变样效应，另一篇描述了细胞分裂中倍性变化后的副突变--挑战我们理解这些案例如何融入解释副突变分子基础的发展范式（赫尔曼等人，2003; Mittelsten沙伊德等人，2003年）。总之，这些研究表明，副突变和其他类型的染色质水平的基因expression.Paramutation的表观遗传调控之间的联系是一个等位基因的相互作用，其中一个等位基因，称为paramutagenic，导致一个同源paramutable等位基因的表达的遗传变化。不受副突变等位基因影响的等位基因称为中性等位基因。将携带副突变等位基因的植物与携带副突变等位基因的植物杂交导致易感等位基因的基因表达降低。当这些杂交种与携带有准突变等位基因的植物异交时，大多数后代在这一代和下一代中表现出低表达表型，表明准突变等位基因的表达状态发生了可遗传的变化。在某些情况下，以前的副突变等位基因变成副突变，现在可以沉默其他副突变等位基因;这被称为继发副突变。因此，副突变有两个不同的步骤：建立和维持。当副突变等位基因暴露于副突变等位基因时，
Paramutation has been studied extensively in maize since RA Brink described a heritable alteration of the r locus that defied principles of Mendelian inheritance (Brink, 1956). A recent publication on paramutation in maize now provides convincing evidence that chromatin-level regulation underlies the phenotypic differences between alleles that participate in paramutation (Stam et al., 2002a). Two additional articles—one detailing paramutation-like effects associated with mammalian imprinting and the other describing paramutation after a change in ploidy in Arabidopsis—challenge us to understand how these cases fit into the developing paradigm explaining the molecular basis for paramutation (Herman et al., 2003; Mittelsten Scheid et al., 2003). Together, these studies suggest a mechanistic link between paramutation and other types of chromatin-level epigenetic regulation of gene expression.Paramutation is an allelic interaction in which one allele, referred to as paramutagenic, causes a heritable change in the expression of a homologous paramutable allele. Alleles unaffected by exposure to a paramutagenic allele are called neutral alleles. Crossing a plant carrying a paramutable allele with a plant carrying a paramutagenic allele results in reduced gene expression of the susceptible allele. When these hybrids are outcrossed to plants carrying paramutable alleles, most of the progeny exhibit the low-expression phenotype in this and the following generations, demonstrating a heritable change in expression state for the paramutable allele. In some cases, the formerly paramutable allele becomes paramutagenic and can now silence other paramutable alleles; this is called secondary paramutation. Thus, there are two distinct steps in paramutation: establishment and maintenance. Establishment occurs when the paramutable allele is exposed to the paramutagenic allele and the paramutable allele takes on